Operating principle:
Dissolved CH4 molecules diffuse through a custom made thin film membrane into the internal gas circuit leading to a detector chamber, where the CH4 concentration is determined by means of Tunable Diode Laser Absorption Spectroscopy (TDLAS). Concentration dependent laser light intensities are converted into the output signal from calibration coefficients stored in firmware and data from additional sensors within the gas circuit.

High accuracy and stability:
Due to their narrow line-width, the Tunable Diode Laser Detectors have a high accuracy and an ideal selectivity for methane molecules. In addition, they feature a large dynamic range covering background partial pressures up to 40 matm. All detectors are subject to an individual calibration and an in depth quality check in our QA lab before they are integrated into our sensors. The quality of the calibration is then verified individually in calibration tanks. The sensor is stable over a long time as the detector tunes the laser to CH4 absorbing and non-absorbing wavelengths for each measurement thus compensating for potential drift influences.